Beolover provides professional Bang&Olufsen maintenance and restoration services. We give one year warranty on parts and labor. All parts featured on the blog are also available to other enthusiasts for their restoration projects. Please, send an email to beolover@gmail.com or use the contact form on the side bar. Enjoy the blog!

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By popular request (really, I got quite a few emails about this!...;-), I finally completed my Beogram DC motor restoration video! It demon...

Friday, June 2, 2017

Beogram 4000: Gold Plating of Carriage Position Switch Terminals

After restoring the command center (aka 'keypad'...;-) of this Beogram 4000, it was time to restore the carriage position switches. Their functioning is crucial for the Beogram 4000's digital control center and the malfunction of just one of these switches will make it impossible to use the Beogram. Like the keypad switches, they are susceptible to oxidation and gold coating is a reliable remedy for potential contact troubles down the road. This shows the PCB that features the switches after removal of the carriage position indicator assembly:

After removal of the servo motor leads and the two screws that hold it in place, the board can be flipped up:

While the contact tabs look shiny and happy on first glance, their removal reveals oxidation in the contact areas (small black dots):

Electrochemical processes enabled by the humidity in the air acting as electrolyte the terminal metal oxidizes where it is in contact with the opposing contact terminal. Coating with a noble metal like gold is a good idea since it dramatically slows down this process. This shows the terminals after the electroplating process:

And after installation:

All good in the carriage position switches department! On to rebuilding the main PCB and the reservoir and motor capacitors!